稀土元素铈对小麦幼苗镉伤害的防护效应

通过长期暴露（7d,16d)试验和无矿质营养元素竞争短期暴露（24h)试验，研究镉对小麦幼苗生长影响及其生物可利用性，进而研究稀土元素铈对镉造成的小麦损伤的防护效应及生物可利用性的影响。结果表明，镉抑制小麦生长、降低根系及茎叶矿质元素的含量。铈对镉引起的生长抑制及营养障碍无明显的保护作用。但铈可明显降低小麦幼苗茎叶及根系中隔的生物富集量。

The Protective Effects of Cerium on the Damage to Wheat (Triticum aestvum L.)Seedlings Caused by Cadmium

Wheat (Triticum aestivum L.) seedlings were grown 7 days and 16 days in nutrient solution at two concentrations of cadmium (0.4 and 1.0 mg/L) and two concentrations of cerium (0.5 and 10.0 mg/L) in single or factorial combination. The decrease of growth was more pronounced in roots for cadmium treatment and the inhibition became serious in shoots with time going on. The combination of cadmium and cerium resulted in synergist or additive without apparent protective effects on the growth. The content of Ca?Mg?Mn in shoots and roots in treatment was less than that in control and was negatively correlated with cadmium concentrations in medium, while the content K?Cu?Zn?P changed little. The combination of cerium and cadmium had no apparent effect on the increase of the content of Ca?Mg?Mn. There were no apparent protective effects on the nutrient disturbance caused by cadmium. However, when cadmium was applied singly, plant accumulated a large amount of cadmium from the solution and the content of cadmium in shoots and roots was positively correlated with cadmium exposure concentrations and exposure time. The addition of cerium obviously reduced the accumulation of cadmium in shoots and roots of the seedlings. The integral uptake rate and the translocation rate also decreased in the presence of cerium, so it protected the seedlings from cadmium accumulation. This was confirmed by the time course of metal accumulation in short-term and no-mineral nutrient competitive experiment. Ten-day seedlings growing in full nutrient solution were transferred to distilled water supplemented with 2 mg/L cadmium, 5 mg/L cerium and 2 mg/L cadmium+5 mg/L cerium respectively for 24 h exposure. When two metals were simultaneously applied, cadmium accumulated in roots and shoots decreased greatly, as compared with the single application of cadmium. It proved that urder long-term exposure Ce reduced the bioaccumulation of Cd.